This invention relates generally to refrigerator air circulation systems and more particularly to an improved air circulation system for independently controlling the operation of an evaporator fan based on the status of either the fresh food compartment or the freezer compartment of a refrigerator.
Conventional dual compartment refrigerators of the forced air circulation type utilize a single evaporator and an evaporator fan for cooling a freezer compartment thereof. The freezer compartment is coupled by a plurality of air passages through a divider wall to a fresh food compartment. An air baffle is located within the fresh food compartment air inlet passage wherein the baffle is operable to control the passage of refrigerated air into the fresh food compartment.
Typically, the operation of the compressor and evaporator fan is controlled by a single thermostat which may be positioned in either the fresh food compartment or the freezer compartment. When the thermostat calls for additional cooling, the evaporator fan, a compressor and a condenser fan are all energized.
It has been found desirable, however, to provide a refrigerator having a fresh food compartment and a freezer compartment wherein the respective compartments are cooled independently from each other. In this configuration, independent operation of the evaporator fan is desired such that the evaporator fan may be energized in response to either the fresh food compartment temperature or the freezer compartment temperature. Further, in this type of refrigerator configuration, it is desirable to selectively operate the baffle to only allow air flow into the fresh food compartment when cooling thereof is required.
U.S. Pat. No. 4,819,442, to Sepso et al., discloses a refrigerator system wherein a temperature sensing unit is interconnected with a baffle to control the position of the baffle in relation to the temperature sensed by the temperature sensing unit. A switch is operatively associated with the baffle for causing a fan to operate only when the valve member is in a certain open position. This system, however, provides no teaching for operating the evaporator fan when either a fresh food compartment or a freezer compartment is calling for cooling. Further, this system is relatively complicated and expensive.
U.S. Pat. No. 4,843,833, to Polkinghorne, discloses a refrigerator having an electronic control receiving inputs from temperature sensors disposed in the freezer compartment and fresh food compartment, respectively. When the freezer is detected to have a temperature exceeding a high temperature limit, the control operates to energize the compressor and evaporator fan. The control further operates to open or close a fresh food baffle dependent on the sensed temperature in the fresh food compartment. This system, however, requires relatively expensive electronics and is relatively complicated.
U.S. Pat. No. 4,732,010, to Linstromberg et al., discloses a refrigerator having an electronic control receiving inputs from temperature sensors disposed in the freezer compartment and fresh food compartment. When the temperature in the fresh food compartment is above a desired fresh food temperature limit, the electronic control operates to open a fresh food baffle and energize an evaporator fan. The control further operates to close the baffle when the fresh food compartment is at or below the desired fresh food compartment temperature. When the freezer compartment temperature is above a high temperature limit, the control operates to energize a compressor and the evaporator fan. This system, however, also requires relatively expensive electronics and is relatively complicated.
It would be an improvement in the art, therefore, if a relatively simple system were provided for independently operating to cool a freezer compartment and fresh food compartment. Specifically, it would be an improvement if an electro-mechanical control system were provided for independently operating an evaporator fan and a fresh food baffle for independently controlling the temperatures of a fresh food compartment and freezer compartment.